invisible fence

I have read the comments regardng invisible fencing and it seems that most JRT owners highly rec. use of a 'real' fence.In our neighborhood, we are not allowed to put up fencing. For this reason, we have installed invisible fencing, and while our JRT is very reluctant to even come near the perimeter of the yard, I am worried that she may still bolt.Our trainer rec. that she will be fine with the invisible fence, but that she should never be left unsupervised.How do the rest of the JRT owners feel about this rec?Bobbie